Screen for attrition-mills



NITED STATES FFIcE.

ATENT THOMAS LEGGETT STURTEVANT, OF FRAMINGHAM, ASSIGNOR TO THE STUR- TEVANT MILL COMPANY, OF BOSTON, MASSACHUSETTS.

SCREEN FOR ATTRlTlON-MILLS, 840.

SPECIFICATION forming part of Letters Patent No. 298,428, dated May 13, 1884-.

I Application filed February 11. 1884. (No model.)

To aZZ whom it may concern:

Be it known that I, THOMAS LEGGETT STUR- TEVANT, a citizen of the United States, residing at Framingham, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Screens for Attrition-Mills, &c.; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this I5 specification.

This invention relates to screens or grates for use in mills for reducing oresor other hard substances in furnaces, and generally for the purpose of screening or sifting various materials.

The essential feature of my invention consists in a grate or screen composed of two elementsnamely, a series of independent removable bars and a permanent backing supporting the same, said backing being grooved or otherwise recessed to receive and steady the bars.

The drawings accompanying this specification represent, in Figure 1, a perspective view.

I Fig. 2 is a section taken through the upper part of the screen shown in Fig. 1.

In said drawings, A represents a band of wrought or cast iron, or other suitable material, perforated with numerous orifices, a a,

5 to permit of free escape of material passing the screen. This band A constitutes the support or backing of the screen proper, and is to be of such form in general outline as shall adapt it to the place it is to occupy.

0 As shown in the accompanying drawings,

the band A is in the general outline of a horseshoe, and as adapted for use in an attritionmill of the class shown and described in Letters Patent of the United States No. 255,550,

5 issued to me on the 28th day of March, 1882. It is in this form that I have practically tested my invention; but I do not of course restrict myself to such form.

As above adapted, the band A is to be supthe object to which it is attached, and its said extremities are formed or provided upon their inner sides with abutments c 0, for purposes hereinafter stated.

The screen or screening-surface,'as shown in said Figs. 1 and 2, is composed of a series of comparatively light bars, (1 d, of steel or other proper material, these bars being arranged inside of and parallel with the longest plane of the backing A, and at such distances apart as may be necessary to properly screen any given material.

To confine the bars (I d firmly in place and maintain uniform spaces between them, I prefer to form them triangular in cross-section, as shown in Fig. 2 of the drawings, and let each partially into a corresponding-shaped groove, 6, formed in the inner face of the backing A.

To crowd the bars d d tightly into the grooves c e, I employ wedges ff, which I insert between the ends of said bars and the abutments. By driving these wedges tightly to place, the bars dd are crowded into the grooves c and firmly held therein. Should it become necessary or desirable to replace one or more of the bars (I d, the wedges are to be removed, which permits such bars to be readily detached. This is effected as follows: After the wedges are removed, the bars at cl are driven out, and the strain and the spring of the steel in the bars d d permit them to yield ,as they pass round the curves of the exterior shell, A.

I prefer the independent bars to any other 85' construction for one reason, among others, that any one of such bars may be replaced by a new one, if necessary, without discarding the remainder.

I claim- A screen composed of the independentremovable bars and the permanent backing supporting the same, said backing being grooved or otherwise recessed to receive and steady the bars, substantially as described.

In testimony whereof I affix my signaturein presence of two witnesses.

THOMAS LEGGETT STURTEVANT.

Witnesses:

H. E. LODGE, A. F. HAYDEN. 

